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Zenodo
2026
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| Acceso en línea: | https://doi.org/10.5281/zenodo.20314279 |
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- <p><b><i>Sphenoderia lenta</i> Schlumberger, 1845</b></p><p><b>Materials examined:</b> 19 examples, tree moss sample, Talle Valley Wildlife Sanctuary, Arunachal Pradesh, India, 27.5340°N, 93.9515°E (Registration No. Pt. 3644/1).</p><p><b>Description:</b> Test is ovoid, hyaline, constructed from regularly overlapping siliceous plates or scales (Fig. 2). The aperture is terminal and lipped, formed by a thin chitinous collar, with one side characteristically inclined inward. Test dimensions range from 61.41 ± 1.24 µm to 64.22 ± 1.24 µm in length and 36.24 ± 0.26 µm to 36.95 ± 0.26 µm in breadth (Table 1). The test thickness is typically equivalent to the breadth, although it may be 5–10% less. The aperture measures 16.07 ± 1.63 µm to 19.67 ± 1.63 µm. The cytoplasm is colorless and only partially occupies the test interior. One or two contractile vacuoles are commonly present. A large, posteriorly positioned nucleus is commonly observed and it contains one or two pale nucleoli. The average dimensions of siliceous plates are 11.38 ± 0.56 µm in length and 7.00 ± 0.52 µm in breadth (Table 2). Pseudopodia, although rarely observed, are long, filose, delicate and sometimes forked. The aperture is distinguished by a prominent collar or neck structure. Where the collar meets the test, the aperture is slender and narrow with rounded, semicircular ends. In lateral view, the collar exhibits a conical profile due to the convergence of its flat sides. In broad view, the outer margin of one side is concave, and its outline is marked by two diagonal lines originating from the outer corners, indicating the inward bend of one lip. Two types of neck morphology are observed at various viewing planes: one tapers gradually from the collar if viewed from lateral side, while the other features a deep notch or rounded depression where it joins the test, if viewed from dorsal. The collar typically appears smooth under light microscopy, but minute scales are properly visible in SEM.</p><p><b>Distribution:</b> The Species distribution list is in Table 7.</p><p><b>Remarks:</b> Earlier studies have reported the different size dimensions of <i>S. lenta</i>, viz., 49–51 × 30–33 µm (Charman <i>et al.</i> 2000), 30–64 µm (Corbet 1973), 47–55 × 35–40 µm (Ogden & Hedley 1980), 35–55 × 24–40 µm (Ogden 1984), 38–59 × 23–45 µm (Todorov & Bankov 2019), 56.4 ± 2.2 × 35.1 ± 1.7 µm (Chatelain <i>et al</i>. 2013). Likewise, in our study, morphometric data indicate a close similarity with the observations of Corbet 1973 and Todorov & Bankov 2019.</p>